Long-term incidence of hypothyroidism after radiotherapy in patients with head-and-neck cancer.

Abstract

PURPOSE:

To determine the long-term incidence of postirradiation hypothyroidism (HT) in patients with head-and-neck cancer.

METHODS AND MATERIALS:

The incidence of overt HT was assessed prospectively in 391 patients with nonthyroid head-and-neck cancer admitted for radiotherapy (RT) consecutively between 1990 and 1996. Eighty-three patients were excluded from the analysis because of known thyroid disease before treatment (n = 27), no RT was given (n = 15), or inadequate follow-up (n = 41). Overt HT was defined as increased thyroid-stimulating hormone (TSH) in combination with decreased fT4/T4 or in combination with initiation of thyroxine replacement therapy.

RESULTS:

With a median follow-up of 4.2 years (range, 3 months to 10.9 years) for 308 evaluable patients, the 5- and 10-year Kaplan-Meier actuarial risks of HT were 20% and 27%, respectively. The median time until development of HT was 1.8 years (3 months to 8.1 years). Multivariate analysis showed that patients with bilateral RT to the neck had a higher risk of HT in comparison with unilateral neck RT (relative hazard, 0.37; p = 0.02). The addition of surgery to RT increased the overall risk of HT (p < 0.001); and if surgery involved the thyroid gland, the relative hazard was 4.74 (p < 0.001). For an elevated pre-RT TSH value, the relative hazard was 1.58 (p < 0.001).

CONCLUSION:

The incidence of overt HT after locoregional RT for nonthyroid head-and-neck cancer continues to increase with time, even after long-term follow-up. We recommend life-long TSH testing in these patients.

• Authors: Roger Tell, Göran Lundell, Bo Nilsson, Helena Sjödin, Freddi Lewin, Rolf Lewensohn
• Journal: International journal of radiation oncology, biology, physics (Int J Radiat Oncol Biol Phys) Vol. 60 Issue 2 Pg. 395-400 (Oct 01 2004) ISSN: 0360-3016 [Print] United States
• PMID: 15380571 (Publication Type: Journal Article)

Topics

• Adult
• Aged
• Aged, 80 and over
• Analysis of Variance
• Female
• Head and Neck Neoplasms (radiotherapy, surgery)
• Humans
• Hypothyroidism (etiology)
• Incidence
• Male
• Middle Aged
• Proportional Hazards Models
• Prospective Studies
• Radiotherapy (adverse effects)